A geological reconnaissance of electrical and electronic waste as a source for rare earth metals

The mining of material resources requires knowledge about geogenic and anthropogenic deposits, in par- ticular on the location of the deposits with the comparatively highest concentration of raw materials. In this study, we develop a framework that allows the establishment of analogies between geological and anthropogenic processes. These analogies were applied to three selected products containing rare earth elements (REE) in order to identify the most concentrated deposits in the anthropogenic cycle. The three identiﬁed anthropogenic deposits were characterised according to criteria such as ‘‘host rock’’, ‘‘REE mineralisation’’ and ‘‘age of mineralisation’’, i.e. regarding their ‘‘geological’’ setting. The results of this characterisation demonstrated that anthropogenic deposits have both a higher concentration of REE and a longer mine life than the evaluated geogenic deposit (Mount Weld, Australia). The results were fur- ther evaluated by comparison with the geological knowledge category of the United Nations Framework Classiﬁcation for Fossil Energy and Mineral Reserves and Resources 2009 (UNFC-2009) to determine the conﬁdence level in the deposit quantities. The application of our approach to the three selected cases shows a potential for recovery of REE in anthropogenic deposits; however, further exploration of both potential and limitations is required.


Introduction
Metallic raw materials are crucial to modern society: their mobilisation increased almost 19-fold from 1900 to 2005 (Graedel et al., 2012). With remarkable selectivity, people have sought the local concentration of specific raw materials in the Earth's crust to satisfy increasing demand. Considering the lifespan of the planet, the exploitation of these ores 1 is a recent phenomenon, but it increased exponentially during the last two hundred years (Arndt and Ganino, 2012). Once these geological heritages are consumed, they cannot be replaced in any period significant to human beings (McLaughlin, 1956), since geogenic mineral deposits are the end product of the prolonged formation of local environmental and geodynamic settings (Dill, 2010). Minerals are individual components within rocks that are generally defined according to their chemical composition and crystal structure (Nickel, 2005). They are the starting point for the production of metals such as rare earth elements (REE). REE are considered geochemically scarce 2 although they are more abundant in the Earth's crust than many other metals (Hoatson et al., 2011;Wäger et al., 2012). Nevertheless, REE are regarded as prominent geological heritage (Hoatson et al., 2011), because they have properties required in current and future technologies and presently cannot be substituted by other metals (National Research Council, 2008;Graedel et al., 2013). The demand for REE is continually increasing (USDOE, 2011), with a high risk of supply disruption (Izatt et al., 2014). For example, the demand of Neodymium-Iron-Boron permanent magnets is expected to increase by 12.5% annually until 2035. The use of phosphors with REE is expected to increase at an annual rate of 8% by 2015. Thereafter, an annual decline by 4.5% is expected until 2035 (Alonso et al., 2012). Both of these components, magnets and phosphors, are used in electrical and electronic equipment (EEE). This use has led to a rapidly increasing volume of REE deposits in waste electrical and electronic equipment (WEEE) over the last few years (Oswald and Reller, 2011). With current recycling technologies, less than 1% of the applied REE can be recovered (UNEP, 2011(UNEP, , 2013. Accordingly, today REE follow a nearly linear resource flow from design to eventual landfill disposal along the material life cycle (Curran and Williams, 2012) and are at risk of being dissipated 3 (Wäger, 2011a). According to Graedel et al. (2011) andUNEP (2010), the material life cycle describes the path of a metal over the various life stages from refining to product manufacturing, to use, end-of-life (EoL), and waste management. Along this path, the metal undergoes several concentration and dilution steps: while refining, the pure metal concentrates, during manufacturing it dilutes slightly and during use the metal dilutes heavily . Through recovery, the pure metal is concentrated, else further dilution can occur. To move from a linear to a circular material flow (Curran and Williams, 2012), material recovery needs to be facilitated with minimised dissipative losses (Oswald and Reller, 2011). To enhance material recovery in the future, it is pivotal to shed light on the process chain from mining to waste management (Brunner, 2011;Simoni, 2012;Wäger et al., 2011b;UNEP, 2013). In particular, both mining of the geosphere and anthroposphere require knowledge about mineable deposits (Lederer et al., 2014). In the study presented here, we develop a framework that allows the establishment of analogies between geological and anthropogenic processes. Based on this framework, analogies between mining of the geosphere and anthroposphere are derived for the case of REE and used to identify the most concentrated deposits for three selected EoL products containing REE components. The three identified deposits are characterised and evaluated with ''geological'' approaches.

Geological approaches for characterisation and evaluation of geogenic deposits
In geology, deposits are characterised to provide a basic understanding of ore deposits' formation and the abundance of minerals. A characterisation includes different attributes describing geological features, such as the location, geological provenance, host rock, mineralisation, source and age of mineral and genetic modelling (Hoatson et al., 2011).
On this basis, different classification schemes have been developed that allow a comparison between the different ore minerals (Long et al., 1998). A widely applied scheme is the so-called ''genetic classification'' of ore deposits. The genetic classification is based on a description of various mineralisation criteria and/or associated geological events, i.e. ore forming processes (Arndt and Ganino, 2012;Hoatson et al., 2011;Pohl, 2011).
In order to evaluate mineral reserves and resources, a globally harmonised and universally applicable classification framework has been developed by international experts from different country-specific classification frameworks: The United Nations Framework Classification for Fossil Energy andMineral Reserves andResources 2009 (UNFC-2009 classification) (UNFC, 2010). This classification evaluates resources based on three dimensions: socio-economic viability, project feasibility and geological knowledge. Within this framework, the dimension ''geological knowledge'' encompasses four levels, which assign different levels of confidence to the quantities of a deposit (Table 1). For potential mining, both mining of the geosphere and anthroposphere require quantities that can be determined with at least low level of confidence, i.e. between levels G1-G3. In contrast, if the quantities are only estimated, respectively cannot be determined with a low level of confidence, no mining can commence. Then level G4 is assigned to the potential deposit.

Framework development
To establish and verify the relationship between geological and anthropogenic processes, four consecutive workshops were organised with four experts: two geologists and two resource management researchers from academia. The knowledge generation process commenced by critically analysing, identifying and discussing the processes of the geologic ore deposit formation, i.e. genetic ore deposit formation understanding and its resulting classification. On this basis, mining, processing and the material lifecycle processes were analysed, deconstructed and categorised. This was followed by the development of a commonly agreed overview framework. The initial framework was then independently synthesised and resynthesized. To verify the emerged framework the same experts were re-consulted (Jabareen, 2009).

Identification of analogies
The analogies, i.e. similarities or correspondences between elements of the framework, were identified in discussions with the above mentioned experts from geology and resource management (Börjeson et al., 2006). The analogy considered to be most relevant was further elaborated for the case of REE in WEEE, which required a specification both of the crust-surface geochemical cycle and of the product cycle.

Development of characterisation and evaluation approach for three REE EoL products
To determine the anthropogenic deposit characteristics, typical geogenic deposit characterisation approaches were identified and critically analysed through literature research. To select a meaningful geological deposit characterisation and evaluation, the same experts as within the framework development were consulted (Börjeson et al., 2006).
This consultation led to a critical analysis of the ''geological setting'' of geogenic deposits according to Hoatson et al. (2011). Overall, the characterisation of the ''geological setting'' provides a continually narrowing and comprehensive understanding of a geogenic deposit with a focus on its associated minerals and different life-stages. Specifically, to enable this perspective the critical analysis was concluded with a selection of criteria that allow the characterisation of the ''geological setting''. These criteria encompass: the geographical ''location'' of the deposit; the ''geological context'', instead of the repetitive criteria ''geological setting''; the ''host rocks''; and the ''REE mineralisation'' and the ''age of mineralisation'' ( Table 2). The criteria describing ''source of REE'' and ''genetic modelling'' were not included. The former is redundant with the specific REE deposit selection and the latter provides a strong congruence with the criterion ''host rock''. The characterisation of the ''geological setting'' concludes with the criterion ''current status''. Those criteria that passed this analysis were adapted for mining of anthroposphere. The selected criteria were first applied to an example geogenic REE deposit as described by Hoatson et al. (2011) and then to three EoL products of anthropogenic deposits: (i) Neodymium-Iron-Boron permanent magnet, (ii) fluorescent lamp with phosphors containing Europium and (iii) fibre optic cable doped with Erbium.
For the evaluation of the anthropogenic deposits, the UNFC-2009 classification (UNFC, 2010) was selected. This classification was critically analysed, and then the category ''geological knowledge'' was chosen on common agreement between the four experts and the principal investigator (Jabareen, 2009).

Framework development
The identified framework shows the relationship between the perspectives of the ''simplified crust-surface geochemical cycle'', ''mining'', ''processing'' and ''product cycle'' (Fig. 1). It lays the foundation for establishing analogies between geological and anthropogenic processes.
The framework connecting the geological and anthropogenic cycles can be described as follows: The simplified crust-surface geochemical cycle adapted from Hoatson et al. (2011) constitutes the foundation of the mining of the geosphere. During this cycle, the ''Magmatic rocks'' are ''altered'' and deconstructed by ''weathering'', then ''transported'' and ''deposited'' as ''sedimentary rocks'' (Hamblin and Christiansen, 2004). This is followed by a mineralogical modification of the rock structure through ''diagenesis 4 '' at low pressure and temperature, and through ''metamorphism 5 '' at high pressure and temperature, into ''metamorphic rocks'' (Kornprobst, 2002). These rocks are melted at high temperature and crystallise into ''Magmatic rocks'' (Berner and Berner, 2012). Within the crust-surface geochemical cycle, any rocks can potentially be mined.
Mining is the subsequent process. According to Mudd (2009), the mining site has to be ''explored'' first, which is followed by an ''evaluation'', e.g. after the mineral reserve/resources classification by UNFC (2010). Then, the mining process needs to be ''developed'' before the ''operation'' can commence. Lastly, the mine site needs to be ''rehabilitated'' to its surface original condition (Mudd, 2009).
In the product cycle as described by Du and Graedel (2011), the ''raw material'' is ''manufactured'' into a ''product'' which is ''used'' until it reaches the ''end-of-life'' stage. Then, through ''waste management'' raw material can be produced again, which leads into a new product cycle. Within this cycle the processes ''manufacturing'' and ''use'' are for a specific purpose: the use of products. Consequently, these products cannot be mined, with the exception of residues and scraps. In contrast, when a product reaches the ''EoL product'' deposit, it loses its specific purpose and could be mined. This means that for the processes in ''waste management'', i.e. starting at the ''EoL product'' via ''waste management'' to ''raw Table 2 Criteria characterising the ''geological setting''.

Criteria Explanation
Geological perspective Product cycle perspective Location Short overview of the place of the geogenic or anthropogenic deposit.

Geological context
The process of the formation of the geological area around the deposit, with focus on identifying potential ''host rocks''. An illustration can be included to visualise the formation of the ''host rock''.
The process of the formation of the local environment of the deposit, with focus on identifying potential host product group, e.g. laptop. An illustration can be included to visualise the location of the ''host rock/ product group''.

Host rock
The process of the formation of the rock, which contains the sought resource, to gain an understanding of the forming process to enable discovery of other deposits with the same ''host rock''.
The process of building the product component, e.g. laptop screen, which contains the sought resource and potential hazardous substances, to gain an understanding of the matrix forming process, to allow for the discovery of other deposits with the same host product components.

REE mineralisation
The process of concentration and its resulting specification of the existing mineral to obtain a detailed understanding of the formation of the ore to estimate the grade thereof.
The process of past, current and expected concentration of the resource and potential hazardous substances and their resulting specification; e.g. mineralisation of materials in laptop screen, to obtain a detailed understanding of the formation of the resource to estimate the grade thereof.

Age of mineralisation
The period when the deposit was formed, or when the mineral was concentrated. This belongs to a general description of a deposit; it can enable an indication of where other similar deposits were formed during the same period of mineralisation. This is relevant for both local and global deposits.
The period when the deposit was formed and its expected future growth, e.g. formation time of a laptop deposit. This gives a general overview of the age of deposits but also indicates future deposits both locally and globally.

Current status
The current development state of the geogenic or anthropogenic deposit with regard to potential mining, and information on the mine life if available.
material'', the same principles apply as for genetic deposit understanding and subsequently its classification (Hoatson et al., 2011).

Identified analogies
The experts found the analogy between the processes ''alteration, weathering, transportation, deposition'' and the process ''use'', and their corresponding concentration -dilution profiles for the geogenic and anthropogenic, to be most relevant. Accordingly, this analogy was further elaborated for the case of REE in WEEE, considering the development of the ratio between the total area occupied by a certain amount of geogenic and anthropogenic deposit (measured in specific surface area (m 2 /kg)), as a possible representation for the (spatial) concentration-dilution or spread profiles.

Specification of the geochemical cycle and of the product cycle
To further elaborate on the analogy for REE, the crust-surface geochemical cycle had to be specified (Fig. 2). The genetic formation of REE consists of four major mineral-system associated geogenic REE deposits: the ''Magmatic 6 '', ''Regolith 7 '', ''Basinal 8 '' and ''Metamorphic''. These four deposits differ from the three types of rocks identified in the framework (Fig. 1). The analogy is formed by specifying the process chain from the ''Magmatic deposit'' via  the ''Regolith deposit'' to the ''Basinal deposit''. The main processes between the ''Magmatic deposits'' and ''Regolith deposits'' are ''alteration'' and ''weathering'' (Fig. 2). The main processes between the followed by deposits ''Regolith'' and ''Basinal associated mineral-system'' are ''transportation'' and ''deposition''. The ''alteration'', ''weathering'', ''transportation'' and ''deposition'' processes can either lead to a concentration or a dilution, depending on the circumstances. For example, the existence of a common transportation channel combined with an ideal deposition environment results in spatial concentration, while diverse transportation routes combined with many different options for mineral deposition result in spatial dilution.
Similarly, the product cycle was specified in the three anthropogenic deposits, ''product deposit at retailer'', ''EoL deposit at user'' and ''deposit at recycler'' and the two processes ''use'' and ''transportation to recycler'' between these deposits. The ''use'' process was identified to correspond to ''alteration'' and ''weathering'', the ''transportation to recycler'' process to ''transportation'' and ''deposition. Consequently, the ''use'' phase is characterised by changes in a local environment with specific boundaries, e.g. using a product in a country. The used products can become concentrated at their EoL (in this paper, this term is used to mean the point at which the last holder no longer has any use for the item). This can lead to the formation of the ''EoL deposit''. Such anthropogenic ''deposits'' are generally formed at each product user. Considering the much larger number of users than manufacturers, scarce metals contained in products are spatially diluted or higher spatial spread (Fig. 3). EoL products can be ''transported'' and form a ''deposit at recycler''. The far smaller number of recyclers compared to consumers result in a spatial concentration or lower spatial spread.

Synthesis of analogies for selected REE EoL products
Three REE EoL products were selected as case studies for an exemplary application of the analogy on anthropogenic deposits. All products are used in a different local environment, i.e. their use is either mobile, stationary or inaccessible. The first, Neodymium, is contained in Neodymium-Iron-Boron permanent magnets used in (electrical) cars, which are mobile during their use and at their EoL are ''transported'' to recyclers at fixed locations for depollution and dismantling. The second, Europium, is contained in phosphors mainly used in fluorescent lamps that are fixed during use and also transported to recyclers for processing. The third, Erbium, is contained in optical fibres used mainly in underground cables. Fig. 3a-c shows the concentration-dilution profiles for the three case studies addressed. For Neodymium-Iron-Boron permanent magnets and phosphors fluorescent lamps, the concentration decreases from the ''deposit at retailer'' to the ''EoL deposit at user'', while it increases again from the ''EoL deposit at user'' to the ''deposit at recycler''. For underground fibre optic cables, the concentration decreases from the ''deposit at retailer'' to the ''deposit EoL at user''; there is no ''deposit at recycler'', because a collection system currently does not exist.

Development of characterisation and evaluation approach for selected REE EoL products
For each of the three case studies the geological setting was characterised according to the criteria defined in Table 2. For the characterisation, the anthropogenic deposits with the maximal concentration, i.e. lowest spread, of REE EoL products were chosen, i.e. the ''deposit at recycler'' for the electric car with Neodymium-Iron-Boron permanent magnet and the fluorescent lamp, and the ''deposit EoL at user'' for the fibre optic cable.
The characterisation of the ''geological setting'' allows a better understanding of the recycling and disposal phase of an EoL product. In particular, it allows the identification of potential for reducing dissipation of the anthropogenic deposits. It further enables a product-centric perspective, as proposed by UNEP (2013), because the focus of characterising the ''geological setting'' begins with the product, e.g. electrical car (Table 3). For the three case studies investigated, the characterisation of the ''geological setting'' demonstrates that There are geogenic REE within Switzerland held as ores in the ''host rock'' but they will not be economically exploitable (Simoni, 2012) within a reasonable time frame.
The total quantity of REE in the anthropogenic deposits in Switzerland is much smaller than in a geogenic deposit but with higher mass fraction of raw material, and therefore likely to be more economically viable (Fig. 4).
The quantity and mass fraction of REE within the investigated anthropogenic deposits of Switzerland and within one geogenic deposit Mt. Weld in Australia are, Neodymium: 2691t deposit Switzerland @ 27 weight-% and 9.88 Mt central lanthanide deposit Mt. Weld Australia @ 0.85 weight-%; Europium: 76,420t deposit Switzerland @ 0.6 weight-% and 9.88 Mt central lanthanide deposit Mt. Weld Australia @ 0.02 weight-%; and Geological context A steeply plunging cylindrical carbonatite complex enclosing REE, which intrudes the central part of the linear graben-like zone. This zone has been overprinted by greenschist facies a metamorphism in Yilgarn Craton, Western Australia.
>70 end-of-life vehicle (ELV) recycling sites (Fig. 4) ( Blaser et al., 2012). The number of recycling business is increased in urban areas. They sort the vehicle into spare parts and scrap (Blaser et al., 2012).
Four recyclers (Fig. 4) under contract by an independent Swiss Light Recycling Foundation: SLRS (Empa, 2012). The recyclers separate the end-oflife fluorescent lamp into four fractions: aluminium-end-cap, glass chips glass-fraction and distilled phosphors, which last two fractions contain mercury (Hug and Renner, 2010).
Implemented along the road and train network until it reaches a building with elevated concentrations in urban areas and between cities. In urban areas the hotspots occur at roads, businesses hubs and public organisations.
Host rock The carbonate has been leached and removed by groundwater activity, thus the relict igneous minerals concentrated. The remaining rock encloses phosphates, iron and manganese bearing oxides containing evaluated REE but also the radioactive elements uranium and thorium.
Electrical car motor hosts the Neodymium bearing permanent magnet . The motor is placed at the back or front of a car. Within a motor the Nd can be concentrated at various positions, depending on the design of a motor.
Inside a fluorescent lamp, the Eu and mercury are hosted at elevated mass fractions within the phosphors. In the phosphors, the Eu is homogeneously distributed.
The fibre optic cable is part of underground pipelines and building connections that hosts the Er. It is protected with several layers of slipcovers to prevent cracking but enable bending. The quartz glass is doped with Er (Angerer et al., 2009).
By 2030, the Neodymium-Iron-Boron permanent magnet deposit is expected to contain Nd 2 Fe 14 B 2691t @ 27 weight-% Nd and 15,143t @ 27 weight-% Nd by 2050 (de Haan et al., 2013), (Fig. 5). The amount of magnet depends strongly on the application of the motor.

Age of mineralisation
The carbonatite intrusive was part of a local alkaline magmatic event about 2025 million years ago. This carbonate intrusive was concentrated by a Permian glaciation event, which allowed the surface of the rich carbonatite intrusion to be exposed for concentration. This event is understood to have occurred about 65.5 million years ago.
At the end of 2010, the first series of electrical cars with Neodymium-Iron-Boron permanent magnet were introduced into in the mass market. The breakthrough of one million electrical cars produced is estimated to be in 2017 (de Haan et al., 2013). It is estimated these deposits may increase in the future more than 700% (Alonso et al., 2012).
The fluorescent lamp with Eu has been patented in 1973 (Blasse and De Vries, 1973). The demand for Eu is expected to increase during the switch from high-volume halogen fluorescent lamp to compact fluorescent lamp (USDOE, 2011;Binnemans et al., 2013). It is expected that the volume of Eu deposits will increase in the future.
Fibre optic cable with Er was described in 1990 (Suzuki, 1990in Yoneyama, 1994. The average mine life is expected to be 50 years (Müller et al., 2013) and an exponential application growth at least until 2030 (Angerer et al., 2009).

Current status
Advanced economic deposit including stockpiling of different grade ores in 2011. In 2012 temporary operating license enabled chemical separation in Malaysia to produce the REO (Machacek and Fold, 2014). The mine life is expected to be at least 20 years.
The motors of electrical cars are currently shredded by metallic machineries.
The recovery of Neodymium-Iron-Boron permanent magnet is currently under research for reuse and recycling (Schüler et al., 2011). Additionally, there is yet no commercial recovery development (Binnemans et al., 2013).
Currently, the phosphors including Eu is disposed underground with the option for retrieval (Huber and Schaller, 2013). However, in September 2012, Europium recycling facilities commence its operation (Solvay, 2012).
Currently the fibre optic cable is implemented for its use and it is estimated that it is unlikely to develop any recycling by 2030 (Angerer et al., 2009). a Greenish rock that is formed under the lowest temperatures and pressure usually produced through regional metamorphism (Encyclopaedia Britannica, 2014).
Furthermore, the anthropogenic deposits of Neodymium-Iron-Boron permanent magnets and fibre optic cable with Er (Angerer et al., 2009) are expected to grow for at least the next 20 years, which is more than the current estimate of 20 years mine life of the Mt. Weld geogenic deposit (Hoatson et al., 2011). Additionally, mining the REE held in these so-called ''anthropogenic deposits'' is likely to involve considerably fewer social and environmental impacts than the extraction from the present major mined, geogenic deposits (Alonso et al., 2012). These geogenic deposits often contain accumulations of radioactive thorium and uranium (Hoatson et al., 2011) (see Fig. 5).
Considering the high mass fractions, long mine life and fewer social and environmental impacts with the expected supply constraints of Nd (Roelich et al., 2014) and Eu (USDOE, 2011), which both have limited or no substitution options (Graedel et al., 2013), it is important to develop strategies and a common platform between mining of the geosphere and anthroposphere. Furthermore, for Neodymium-Iron-Boron permanent magnets, the results demonstrate that with the current recycling technology of metallic shredders Nd cannot be recovered . Considering the high mass fractions, at present only the Er within the fibre optic cable in Switzerland can be considered as geochemically scarce. Since the Er fibre optic cable applications are expected to increase exponentially (Angerer et al., 2009), the Er will be distributed and consequently diluted further within Switzerland's ground and buildings until after 2030.
The characterisation of the ''geological setting'' of anthropogenic deposits was demanding. The criterion ''host rock'' can be valid for different levels of product components. For example, considering an electrical car with Neodymium-Iron-Boron permanent magnets, the ''host rock'' could apply to the electrical car and  also to the motor. In such a case, a bottom-up approach was applied. Accordingly, first the ''REE mineralisation'' was identified, i.e. Neodymium-Iron-Boron permanent magnet, followed by the resulting ''host rock'', i.e. motor. To increase the accuracy of characterising the ''host rock'' or ''mineralisation'', it is important to exchange transparent information through the entire ''product cycle'' from design via manufacturing to waste management. For instance, the implementation of a feedback loop from end-of-life to decision makers is limited (Fakhredin et al., 2013). Information on such matters is critical in determining a comprehensive understanding of ''age of mineralisation'', which includes the future growth of a deposit formation. This, in turn is important for identifying the economic viability of a future mine (UNFC, 2010). Hence, key performance indicators are a crucial support for a practical implementation and should be physically-, economic-and environmentally-based as proposed by the UNEP (2013). Moreover, Winterstetter et al. (2015) concluded that future research is required to develop a standardised procedure for characterising any kind of geogenic and anthropogenic deposits. Additionally, it is crucial to develop a common platform for characterising and evaluating geogenic and anthropogenic deposits. Therefore, the characterisation of the ''geological setting'' and its evaluation of the ''geological knowledge'' (Table 4) lay a foundation.
Based on this foundation, the evaluation showed that, the Neodymium-Iron-Boron magnets and the fibre optic cables can be considered to be potential deposits for Nd (category G3) and Er, respectively (category G4). The deposit containing Eu is classified as a known deposit of category G1 like the geogenic deposit Mt. Weld. This is a first step in completing the level of proven resources for developing a mining of the anthroposphere mine, as described for mining of the geosphere (USDOE, 2011;Hoatson et al., 2011).

Conclusions and outlook
In this study, we have attempted to integrate a geological perspective and approaches into the characterisation and evaluation of anthropogenic metal deposits. Our approach allowed the identification of the most concentrated deposits along the anthropogenic cycle, their characterisation with regard to the ''geological'' setting, and the evaluation of the confidence level of the deposit quantities for three cases. Not least, the study was able to provide distinct characterisations for the three investigated REEs. However, the present framework is built on a simple representation of the reality, as e.g. raw material losses (for example REE in fibre optic cables left in the underground) are not represented. A possible next step would consist of further differentiating the processes and exploring how far correspondences between the geogenic and anthropogenic cycles can then still be established. The application is being introduced in the market, thus information of future scenarios including uncertainty is available. Research for recovery is currently being undertaken. No commercial recovery takes place yet.
Information on the future development of the deposit quantity is available. Recovery activities commenced in 2012.
Low information on the precise location of the quantity is available. Currently no research for the recovery is being undertaken.